Method for Detecting Presence of Tubing in Pump Assembly

ABSTRACT

Methods for detecting tubing in a pump assembly of a pump system are provided. For example, a method comprises connecting a power supply to each of a plurality of pump motors of the pump system. Each pump motor of the plurality of pump motors has a power supply cable configured to connect to the power supply and drives a pump head of a plurality of pump heads of the pump system. The method also comprises sensing a motor current from each of the power supply cables, determining whether tubing is loaded in each pump head, and, if tubing is not loaded in a pump head, then disconnecting from the power supply the power supply cable of the pump motor associated with the pump head in which tubing is not loaded. Systems for detecting the presence of tubing within a pump head of a plurality of pump heads also are provided.

FIELD

The present subject matter relates generally to pump assemblies and,more particularly, to methods and systems for detecting the presence oftubing in a pump head of a pump assembly.

BACKGROUND

Lower back injuries and chronic joint pain are major health problemsresulting not only in debilitating conditions for the patient, but alsoin the consumption of a large proportion of funds allocated for healthcare, social assistance and disability programs. In the lower back, discabnormalities and pain may result from trauma, repetitive use in theworkplace, metabolic disorders, inherited proclivity, and/or aging. Theexistence of adjacent nerve structures and innervation of the disc arevery important issues in respect to patient treatment for back pain. Injoints, osteoarthritis is the most common form of arthritis pain andoccurs when the protective cartilage on the ends of bones wears downover time.

A minimally invasive technique of delivering high-frequency electricalcurrent has been shown to relieve localized pain in many patients.Generally, the high-frequency current used for such procedures is in theradiofrequency (RF) range, i.e. between 100 kHz and 1 GHz and morespecifically between 300-600 kHz. The RF electrical current is typicallydelivered from a generator via connected electrodes that are placed in apatient's body, in a region of tissue that contains a neural structuresuspected of transmitting pain signals to the brain. The electrodesgenerally include an insulated shaft with an exposed conductive tip todeliver the radiofrequency electrical current. Tissue resistance to thecurrent causes heating of tissue adjacent resulting in the coagulationof cells (at a temperature of approximately 45° C. for smallunmyelinated nerve structures) and the formation of a lesion thateffectively denervates the neural structure in question. Denervationrefers to a procedure whereby the ability of a neural structure totransmit signals is affected in some way and usually results in thecomplete inability of a neural structure to transmit signals, thusremoving the pain sensations. This procedure may be done in a monopolarmode where a second dispersive electrode with a large surface area isplaced on the surface of a patient's body to complete the circuit, or ina bipolar mode where a second radiofrequency electrode is placed at thetreatment site. In a bipolar procedure, the current is preferentiallyconcentrated between the two electrodes.

To extend the size of a lesion, radiofrequency treatment may be appliedin conjunction with a cooling mechanism, whereby a cooling means is usedto reduce the temperature of the electrode-tissue interface, allowing ahigher power to be applied without causing an unwanted increase in localtissue temperature that can result in tissue desiccation, charring, orsteam formation. The application of a higher power allows regions oftissue further away from the energy delivery device to reach atemperature at which a lesion can form, thus increasing the size/volumeof the lesion. Some systems including electrodes as described above mayinclude multiple electrodes, each configured as a medical probeassembly. Thus, a cooling means may be provided for each of theplurality of probe assemblies, and typical cooling means include a pumpassembly that pumps a cooling fluid to a probe assembly, at least inpart through tubing loaded in a pump head of the pump assembly. Insystems having multiple probe assemblies, each with an associated pumpassembly, a typical approach is to operate all pump assembliessimultaneously, regardless of whether the associated probe assembly isbeing used in a procedure and, thus, requires cooling. Accordingly,known systems usually operate all pump heads even though one or morepump heads of the multiple pump assembly system may not be loaded withtubing.

The treatment of pain using high-frequency electrical current has beenapplied successfully to various regions of patients' bodies suspected ofcontributing to chronic pain sensations. For example, with respect toback pain, which affects millions of individuals every year,high-frequency electrical treatment has been applied to several tissues,including intervertebral discs, facet joints, sacroiliac joints as wellas the vertebrae themselves (in a process known as intraosseousdenervation). In addition to creating lesions in neural structures,application of radiofrequency energy has also been used to treat tumorsthroughout the body. Further, with respect to knee pain, which alsoaffects millions of individuals every year, high-frequency electricaltreatment has been applied to several tissues, including, for example,the ligaments, muscles, tendons, and menisci.

Thus, the art is continuously seeking new and improved systems andmethods for treating chronic pain using cooled RF ablation techniques.For example, improved systems utilizing one or more methods fordetecting whether tubing is loaded in a pump assembly of the system,such that empty or unloaded pump assemblies can be deactivated or turnedoff, would be useful. As another example, systems having a controllerfor controlling a power supply to a pump assembly based on whether thepump assembly has tubing loaded in its pump head would be beneficial.

SUMMARY

Objects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In one aspect, the present subject matter is directed to a method fordetecting tubing in a pump assembly of a pump system. The methodcomprises connecting a power supply to each of a plurality of pumpmotors of the pump system. Each pump motor of the plurality of pumpmotors has a power supply cable configured to connect to the powersupply. Further, each pump motor of the plurality of pump motors drivesa pump head of a plurality of pump heads of the pump system. The methodalso comprises sensing a motor current from each of the power supplycables, determining whether tubing is loaded in each pump head, and, iftubing is not loaded in a pump head, then disconnecting from the powersupply the power supply cable of the pump motor associated with the pumphead in which tubing is not loaded. It should also be understood thatthe method may further include any of the additional features asdescribed herein.

In another aspect, the present disclosure is directed to a system fordetecting the presence of tubing within a pump head of a plurality ofpump heads. The system comprises a plurality of pump assemblies. Eachpump assembly comprises a pump motor, a power supply cable for supplyingpower to the pump motor, and one pump head of the plurality of pumpheads. The pump motor drives the pump head. The system further comprisesa controller for controlling whether power is supplied to the powersupply cable of each pump assembly. The controller is configured forconnecting a power supply to each power supply cable, sensing a motorcurrent from each of the power supply cables, determining whether tubingis loaded in each pump head, and, if tubing is not loaded in a pumphead, then disconnecting from the power supply the power supply cable ofthe pump motor associated with the pump head in which tubing is notloaded. It should also be appreciated that the system may furtherinclude any of the additional features as described herein.

In yet another aspect, the present disclosure is directed to a methodfor detecting tubing in a pump assembly. The method comprises connectinga power supply to a pump motor of the pump assembly. The pump motor hasa power supply cable for connecting to the power supply, and the pumpmotor drives a pump head of the pump assembly. The method furthercomprises sensing a motor current from the power supply cable;transforming the motor current in a time domain to a frequency domain;determining whether tubing is loaded in the pump head and, if tubing isnot loaded in the pump head, then disconnecting the power supply cablefrom the power supply; and calculating a speed of the pump motor iftubing is loaded in the pump head. Determining whether tubing is loadedin the pump head comprises determining how many fundamental frequenciesare observable in the transformed motor current. It should also beunderstood that the method may further include any of the additionalfeatures as described herein.

These and other features, aspects and advantages of the present subjectmatter will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present subject matter, includingthe best mode thereof, directed to one of ordinary skill in the art, isset forth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 provides a schematic illustration of a portion of a system forapplying radiofrequency electrical energy to a patient's body accordingto an exemplary embodiment of the present subject matter.

FIG. 2 provides a perspective view of a pump system of FIG. 1 accordingto an exemplary embodiment of the present subject matter.

FIG. 3 provides a block diagram of the pump system of FIG. 1 accordingto an exemplary embodiment of the present subject matter.

FIG. 4 provides a schematic diagram illustrating a portion of the pumpsystem of FIG. 2 according to an exemplary embodiment of the presentsubject matter.

FIG. 5 provides a flow diagram illustrating a method for detectingtubing in a pump assembly according to an exemplary embodiment of thepresent subject matter.

FIG. 6 provides photographs of an oscilloscope screen, showing a currentdraw waveform for a pump assembly pump motor operating without tubingloaded in a pump head of the pump assembly.

FIG. 7 provides photographs of the oscilloscope screen of FIG. 6,showing a current draw waveform for the pump assembly pump motoroperating with tubing loaded in the pump head of the pump assembly.

DETAILED DESCRIPTION

Reference will now be made in detail to one or more embodiments of theinvention, examples of the invention, examples of which are illustratedin the drawings. Each example and embodiment is provided by way ofexplanation of the invention, and is not meant as a limitation of theinvention. For example, features illustrated or described as part of oneembodiment may be used with another embodiment to yield still a furtherembodiment. It is intended that the invention include these and othermodifications and variations as coming within the scope and spirit ofthe invention.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

For the purposes of the present subject matter, a lesion refers to theregion of tissue that has been irreversibly damaged as a result of theapplication of thermal energy, and the present subject matter is notintended to be limited in this regard. Further, for the purposes of thisdescription, proximal generally indicates that portion of a device orsystem next to or nearer to a user (when the device is in use), whilethe term distal generally indicates a portion further away from the user(when the device is in use).

Generally, the present subject matter provides pump systems, pumpassemblies, and pump heads for pumping fluid to one or more systems orassemblies. More particularly, the present subject matter provides apump system comprising a plurality of pump assemblies, and each pumpassembly of the plurality of pump assemblies supplies a fluid to acooling circuit. The cooling circuit may be used to supply cooling fluidto the distal end of a medical probe assembly for delivering energy to apatient's body, e.g., as part of a treatment procedure. The pump systemfurther comprises a base for supporting the plurality of pumpassemblies. Each pump assembly described herein comprises a pump head, abezel surrounding an outer perimeter of the pump head, a motor, andtubing.

In general, the pump head comprises an occlusion bed, a rotor guide, arotor assembly positioned between the occlusion bed and the rotor guide,and a pathway for tubing. The tubing supplies fluid to the coolingcircuit. The pathway comprises an inlet portion, an outlet portion, anda connecting portion that connects the inlet portion to the outletportion. The inlet portion of the pathway is defined between theocclusion bed and the rotor guide, the outlet portion of the pathway isdefined between the occlusion bed and the rotor guide, and theconnecting portion of the pathway is defined between the occlusion bedand the rotor assembly. Further, the occlusion bed is movable withrespect to the rotor guide and the rotor assembly. As described herein,through such movement of the occlusion bed and other features, the pumphead is configured to ease the task of inserting the tubing into thepump head such that correct insertion of the tubing is repeatable andsafe. Once the tubing is inserted or loaded into the pump head, and theuser is safely separated from the rotor assembly, e.g., by a rotor coverplate and pump head cover as described herein, the motor may be poweredon to drive the rotor assembly and thereby begin pumping the fluidthrough the tubing.

Referring now to the drawings, FIG. 1 illustrates a schematic diagram ofone embodiment of a system 100 of the present subject matter. As shown,the system 100 includes a generator 102; a cable 104; one or more probeassemblies 106 (only one probe assembly 106 is shown); one or morecooling devices 108; a pump cable 110; one or more proximal coolingsupply tubes 112; and one or more proximal cooling return tubes 114. Inan exemplary embodiment, the system 100 includes first, second, third,and fourth probe assemblies 106. As shown in the illustrated embodiment,the generator 102 is a radiofrequency (RF) generator, but optionally maybe any power source that may deliver other forms of energy, includingbut not limited to microwave energy, thermal energy, ultrasound, andoptical energy. Further, the generator 102 may include a display 103(FIG. 2) incorporated therein. The display 103 may be operable todisplay various aspects of a treatment procedure, including but notlimited to any parameters that are relevant to a treatment procedure,such as temperature, impedance, etc. and errors or warnings related to atreatment procedure. If no display 103 is incorporated into thegenerator 102, the generator 102 may include means of transmitting asignal to an external display. In one embodiment, the generator 102 isoperable to communicate with one more devices, for example, with one ormore of the probe assemblies 106 and the one or more cooling devices108. Such communication may be unidirectional or bidirectional dependingon the devices used and the procedure performed.

In addition, as shown, a distal region 124 of the cable 104 may includea splitter 130 that divides the cable 104 into two or more distal ends132 such that the probe assemblies 106 can be connected thereto. Aproximal end 128 of the cable 104 is connected to the generator 102.This connection can be permanent, whereby, for example, the proximal end128 of the cable 104 is embedded within the generator 102, or temporary,whereby, for example, the proximal end 128 of cable 104 is connected togenerator 102 via an electrical connector. The two or more distal ends132 of the cable 104 terminate in connectors 134 operable to couple tothe probe assemblies 106 and establish an electrical connection betweenthe probe assemblies 106 and the generator 102. In alternateembodiments, the system 100 may include a separate cable for each probeassembly 106 being used to couple the probe assemblies 106 to thegenerator 102. Alternatively, the splitter 130 may include more than twodistal ends. Such a connector is useful in embodiments having more thantwo devices connected to the generator 102, for example, if more thantwo probe assemblies are being used.

The cooling device(s) 108 may include any means of reducing atemperature of material located at and proximate to one or more of theprobe assemblies 106. For example, as shown in FIG. 2, the coolingdevices 108 may include a pump system 120 having one or more peristalticpump assemblies 122 operable to circulate a fluid from the coolingdevices 108 through one or more proximal cooling supply tubes 112, theprobe assemblies 106 (via internal lumens therein, as described ingreater detail below), one or more proximal cooling return tubes 114 andback to the one or more cooling devices 108. For example, as shown inthe illustrated embodiment of FIGS. 2 and 3, the pump system 120includes four peristaltic pump assemblies 122 coupled to a power supply126. In such embodiments, as shown in FIG. 3, each of the plurality ofpump assemblies 122 may be in separate fluid communication with one ofthe probe assemblies. The fluid may be water or any other suitable fluidor gas. In alternate embodiments, the pump system 120 may include onlyone peristaltic pump assembly 122 or greater than four pump assemblies122. In addition, as shown in FIG. 3, each of the pump assemblies 122may have an independent speed (i.e., RPM) controller 125 that isconfigured to independently adjust the speed of its respective pumpassembly. The pump system 120 and pump assemblies 122 are described ingreater detail below.

Referring to FIG. 1, the system 100 may include a controller or controlmodule 101 for facilitating communication between the cooling devices108 and the generator 102. In this way, feedback control is establishedbetween the cooling devices 108 and the generator 102. The feedbackcontrol may include the generator 102, the probe assemblies 106, and thecooling devices 108, although any feedback between any two devices iswithin the scope of the present subject matter. The feedback control maybe implemented, for example, in a control module that may be a componentof the generator 102. In such embodiments, the generator 102 is operableto communicate bi-directionally with the probe assemblies 106 as well aswith the cooling devices 108. In the context of the present subjectmatter, bi-directional communication refers to the capability of adevice to both receive a signal from and send a signal to anotherdevice.

As an example, the generator 102 may receive temperature measurementsfrom one or both of the first and second probe assemblies 106. Based onthe temperature measurements, the generator 102 may perform some action,such as modulating the power that is sent to the probe assemblies 106.Thus, both probe assemblies 106 may be individually controlled based ontheir respective temperature measurements. For example, power to each ofthe probe assemblies 106 can be increased when a temperature measurementis low or can be decreased when a measurement is high. This variation ofpower may be different for each probe assembly. In some cases, thegenerator 102 may terminate power to one or more probe assemblies 106.Thus, the generator 102 may receive a signal (e.g., temperaturemeasurement) from one or both of the first and second probe assemblies106, determine the appropriate action, and send a signal (e.g.,decreased or increased power) back to one or both of the probeassemblies 106. Alternatively, the generator 102 may send a signal tothe cooling devices 108 to either increase or decrease the flow rate ordegree of cooling being supplied to one or both of the first and secondprobe assemblies 106.

More specifically, the pump assemblies 122 may communicate a fluid flowrate to the generator 102 and may receive communications from thegenerator 102 instructing the pumps 122 to modulate this flow rate. Insome instances, the peristaltic pump assemblies 122 may respond to thegenerator 102 by changing the flow rate or turning off for a period oftime. With the cooling devices 108 turned off, any temperature sensingelements associated with the probe assemblies 106 would not be affectedby the cooling fluid, allowing a more precise determination of thesurrounding tissue temperature to be made. In addition, when using morethan one probe assembly 106, the average temperature or a maximumtemperature in the temperature sensing elements associated with theprobe assemblies 106 may be used to modulate cooling.

In other embodiments, the cooling devices 108 may reduce the rate ofcooling or disengage depending on the distance between the probeassemblies 106. For example, when the distance is small enough such thata sufficient current density exists in the region to achieve a desiredtemperature, little or no cooling may be required. In such anembodiment, energy is preferentially concentrated between first andsecond energy delivery devices 192 through a region of tissue to betreated, thereby creating a strip lesion. A strip lesion ischaracterized by an oblong volume of heated tissue that is formed whenan active electrode is in close proximity to a return electrode ofsimilar dimensions. This occurs because at a given power, the currentdensity is preferentially concentrated between the electrodes and a risein temperature results from current density. Thus, as illustrated bythese examples, the controller 101 may actively control energy deliveredto the tissue by controlling an amount of energy delivered through theenergy delivery device(s) 192 and by controlling a flow rate through thepump assembly(ies) 122, e.g., the flow rate through tubing of a pumphead 200 of a pump assembly 122.

The cooling devices 108 may also communicate with the generator 102 toalert the generator 102 to one or more possible errors and/or anomaliesassociated with the cooling devices 108. Such errors and/or anomaliesmay include whether cooling flow is impeded or if a lid of one or moreof the cooling devices 108 is opened. The generator 102 may then act onthe error signal by at least one of alerting a user, aborting theprocedure, and modifying an action.

The controller 101, as well as the other controllers or microcontrollersdescribed herein, such as the microcontroller 212 and motor controller214, can include various components for performing various operationsand functions. For example, the controller 101 can include one or moreprocessor(s) and one or more memory device(s). The operation of thesystem 100, including the generator 102 and cooling device(s) 108, maybe controlled by a processing device such as the controller 101, whichmay include a microprocessor or other device that is in operativecommunication with components of the system 100. In one embodiment, theprocessor executes programming instructions stored in memory and may bea general or special purpose processor or microprocessor operable toexecute programming instructions, control code, or micro-control code.The memory may be a separate component from the processor or may beincluded onboard within the processor. Alternatively, the controller 101may be constructed without using a processor or microprocessor, e.g.,using a combination of discrete analog and/or digital logic circuitry(such as switches, amplifiers, integrators, comparators, flip-flops, ANDgates, and the like) to perform control functionality instead of relyingupon software. Components of the system 100 may be in communication withthe controller 101 via one or more signal lines or shared communicationbusses.

Further, the one or more memory device(s) can store instructions thatwhen executed by the one or more processor(s) cause the one or moreprocessor(s) to perform the operations and functions, e.g., as thosedescribed herein for communicating a signal. In one embodiment, thegenerator 102 includes a control circuit having one or more processorsand associated memory device(s) configured to perform a variety ofcomputer-implemented functions (e.g., performing the methods, steps,calculations and the like disclosed herein). As used herein, the term“processor” refers not only to integrated circuits referred to in theart as being included in a computer, but also refers to a controller, amicrocontroller, a microcomputer, a programmable logic controller (PLC),an application specific integrated circuit, and other programmablecircuits. Additionally, the memory device(s) may generally comprisememory element(s) including, but not limited to, computer readablemedium (e.g., random access memory (RAM)), computer readablenon-volatile medium (e.g., a flash memory), a floppy disk, a compactdisc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digitalversatile disc (DVD) and/or other suitable memory elements.

Such memory device(s) may generally be configured to store suitablecomputer-readable instructions that, when implemented by thecontroller(s) or processor(s) 101, configure the control circuit toperform various functions including, but not limited to, controlling anamount of energy delivered through the energy delivery device(s) 192,controlling a flow rate through the pump assembly(ies) 122, and/or otherfunctions. More particularly, the instructions may configure the controlcircuit to perform functions such as receiving directly or indirectlysignals from one or more sensors (e.g. voltage sensors, current sensors,and/or other sensors) indicative of various input conditions, and/orvarious other suitable computer-implemented functions, which enable thegenerator 102 or other components of system 100 to carry out the variousfunctions described herein. An interface can include one or morecircuits, terminals, pins, contacts, conductors, or other components forsending and receiving control signals. Moreover, the control circuit mayinclude a sensor interface (e.g., one or more analog-to-digitalconverters) to permit signals transmitted from any sensors within thesystem to be converted into signals that can be understood and processedby the controller(s) or processor(s) 101.

Still referring to FIG. 1, the proximal cooling supply tubes 112 mayinclude proximal supply tube connectors 116 at the distal ends of theone or more proximal cooling supply tubes 112. Additionally, theproximal cooling return tubes 114 may include proximal return tubeconnectors 118 at the distal ends of the one or more proximal coolingreturn tubes 114. In one embodiment, the proximal supply tube connectors116 are female luer-lock type connectors and the proximal return tubeconnectors 118 are male luer-lock type connectors, although otherconnector types are intended to be within the scope of the presentsubject matter.

In addition, as shown in FIG. 1, the probe assembly 106 may include aproximal region 160, a handle 180, a hollow elongate shaft 184, and adistal tip region 190 that includes the one or more energy deliverydevices 192. The elongate shaft 184 and the distal tip region 190together form a probe 186 that contact a patient's body to deliverenergy thereto. The hollow elongate shaft 184 also may be described asan outer circumferential portion 184 of the probe 186, and the energydelivery device 192 extends distally from the outer circumferentialportion 184. As further described herein, the elongate shaft 184 may bean electrically non-conductive outer circumferential portion 184, e.g.,the shaft 184 may be formed from an electrically non-conductive materialor may be electrically insulated, and the energy delivery device(s) 192may be electrically and thermally-conductive energy delivery device(s)192.

The proximal region 160 includes a distal cooling supply tube 162, adistal supply tube connector 166, a distal cooling return tube 164, adistal return tube connector 168, a probe assembly cable 170, and aprobe cable connector 172. In such embodiments, the distal coolingsupply tube 162 and distal cooling return tube 164 are flexible to allowfor greater maneuverability of the probe assemblies 106 but alternateembodiments with rigid tubes are possible. Further, in severalembodiments, the distal supply tube connector 166 may be a maleluer-lock type connector and the distal return tube connector 168 may bea female luer-lock type connector. Thus, the proximal supply tubeconnector 116 may be operable to interlock with the distal supply tubeconnector 166 and the proximal return tube connector 118 may be operableto interlock with the distal return tube connector 168.

The probe assembly 106 also may include a shaft supply tube 136 and ashaft return tube 138, which are internal lumens for circulating coolingfluid to a distal end of the probe assembly 106. The distal coolingsupply tube 162 and the distal cooling return tube 164 may be connectedto the shaft supply tube 136 and the shaft return tube 138,respectively, within the handle 180 of the probe assembly 106. In oneembodiment, the shaft supply tube 136 and the shaft return tube 138 maybe hypotubes made of a conductive material, such as stainless steel,that extend from the handle 180 through a lumen of the hollow elongateshaft 184 to distal tip region 190. The number of hypotubes used forsupplying cooling fluid and the number used for returning cooling fluidand the combination thereof may vary and all such combinations areintended to be within the scope of the present invention.

As illustrated in FIG. 1, the cooling fluid flows in a cooling circuit140 formed by the cooling device(s) 108, the distal tip region 190 ofthe probe, and the various supply and return tubes 112, 114, 162, 162,136, 138. The arrows FF in FIG. 1 illustrate the direction of flow ofthe cooling fluid supplied by the cooling device(s) 108 through thecooling circuit 140. More specifically, the cooling fluid flows from thecooling device(s) 108, through proximal cooling supply tube 112 todistal cooling supply tube 162, through distal cooling supply tube 162to shaft supply tube 136, through shaft supply tube 136 to the distaltip region 190, from the distal tip region 190 to shaft return tube 138,through shaft return tube 138 to distal return tube 164, through distalreturn tube 164 to proximal return tube 114, and through proximal returntube 114 to the cooling device(s) 108.

Referring still to FIG. 1, the probe cable connector 172 may be locatedat a proximal end of the probe assembly cable 170 and may be operable toreversibly couple to one of the connectors 134, thus establishing anelectrical connection between the generator 102 and the probe assembly106. The probe assembly cable 170 may include one or more conductorsdepending on the specific configuration of the probe assembly 106. Forexample, in one embodiment, the probe assembly cable 170 may includefive conductors allowing probe assembly cable 170 to transmit RF currentfrom the generator 102 to the one or more energy delivery devices 192,as well as to connect multiple temperature sensing elements to thegenerator 102.

In addition, the handle 180 may be operable to easily and securelycouple to an optional introducer tube, e.g., in an embodiment where anintroducer tube would facilitate insertion of the one or more probeassemblies 106 into a patient's body. For instance, as shown, the handle180 may taper at its distal end to accomplish this function, i.e., toenable the handle 180 to securely couple to an optional introducer tube.Generally, introducer tubes may include a proximal end, a distal end,and a longitudinal bore extending therebetween. Thus, the introducertubes (when used) are operable to easily and securely couple with theprobe assembly 106. For example, the proximal end of the introducertubes may be fitted with a connector able to mate reversibly with thehandle 180 of a probe assembly 106. An introducer tube may be used togain access to a treatment site within a patient's body, and the hollowelongate shaft 184 of a probe assembly 106 may be introduced to thetreatment site through the longitudinal bore of the introducer tube.Introducer tubes may further include one or more depth markers to enablea user to determine the depth of the distal end of the introducer tubewithin a patient's body. Additionally, introducer tubes may include oneor more radiopaque markers to ensure the correct placement of theintroducers when using fluoroscopic guidance.

The introducer tubes may be made of various materials, as is known inthe art and, if the material is electrically conductive, the introducertubes may be electrically insulated along all or part of their length,to prevent energy from being conducted to undesirable locations within apatient's body. In some embodiments, the elongate shaft 184 may beelectrically conductive, and an introducer may function to insulate theshaft 184, leaving the energy delivery device 192 exposed for treatment.Further, the introducer tubes may be operable to connect to a powersource and, therefore, may form part of an electrical current impedancemonitor (wherein at least a portion of the introducer tube is notelectrically insulated). Different tissues may have different electricalimpedance characteristics, and therefore, it is possible to determinetissue type based on impedance measurements, as has been described.Thus, it would be beneficial to have a means of measuring impedance todetermine the type of tissue within which a device is located. Inaddition, the gauge of the introducer tubes may vary depending on theprocedure being performed and/or the tissue being treated. In someembodiments, the introducer tubes should be sufficiently sized in theradial dimension so as to accept at least one probe assembly 106.Moreover, in alternative embodiments, the elongate shaft 184 may beinsulated so as not to conduct energy to portions of a patient's bodythat are not being treated.

The system 100 also may include one or more stylets. A stylet may have abeveled tip to facilitate insertion of the one or more introducer tubesinto a patient's body. Various forms of stylets are well known in theart and the present subject matter is not limited to include only onespecific form. Further, as described above with respect to theintroducer tubes, the stylets may be operable to connect to a powersource and may therefore form part of an electrical current impedancemonitor. In other embodiments, one or more of the probe assemblies 106may form part of an electrical current impedance monitor. Thus, thegenerator 102 may receive impedance measurements from one or more of thestylets, the introducer tubes, and/or the probe assemblies 106 and mayperform an action, such as alerting a user to an incorrect placement ofan energy delivery device 192, based on the impedance measurements.

The energy delivery devices 192 may include any means of deliveringenergy to a region of tissue adjacent to the distal tip region 190. Forexample, the energy delivery devices 192 may include an ultrasonicdevice, an electrode, or any other energy delivery means, and thepresent subject matter is not limited in this regard. Similarly, energydelivered via the energy delivery devices 192 may take several forms,including but not limited to thermal energy, ultrasonic energy,radiofrequency energy, microwave energy, or any other form of energy.For example, in one embodiment, the energy delivery devices 192 mayinclude an electrode. The active region of the electrode 192 may be 2 to20 millimeters (mm) in length and energy delivered by the electrode iselectrical energy in the form of current in the RF range. The size ofthe active region of the electrode can be optimized for placementwithin, e.g., an intervertebral disc; however, different sizes of activeregions, all of which are within the scope of the present subjectmatter, may be used depending on the specific procedure being performed.In some embodiments, feedback from the generator 102 may automaticallyadjust the exposed area of the energy delivery device 192 in response toa given measurement, such as impedance or temperature. For example, inone embodiment, the energy delivery devices 192 may maximize energydelivered to the tissue by implementing at least one additional feedbackcontrol, such as a rising impedance value. As previously described, eachenergy delivery device 192 may be electrically and thermally-conductiveand may comprise a conductive outer circumferential surface to conductelectrical energy and heat from the distal tip region 190 of the probe186 to a patient's body. Further, the distal tip region 190 includes oneor more temperature sensing elements, which are operable to measure thetemperature at and proximate to the one or more energy delivery devices192. The temperature sensing elements may include one or morethermocouples, thermometers, thermistors, optical fluorescent sensors orany other means of sensing temperature.

In one embodiment, the first and second probe assemblies 106 may beoperated in a bipolar mode. For example, the distal tip region 190 ofeach of two probe assemblies may be located within an intervertebraldisc. In such embodiments, electrical energy is delivered to the firstand second probe assemblies 106, and this energy is preferentiallyconcentrated therebetween through a region of tissue to be treated(i.e., an area of the intervertebral disc). The region of tissue to betreated is thus heated by the energy concentrated between the first andsecond probe assemblies 106. In other embodiments, the first and secondprobe assemblies 106 may be operated in a monopolar mode, in which casean additional grounding pad is required on the surface of a body of apatient, as is known in the art. Any combination of bipolar andmonopolar procedures may also be used. It should also be understood thatthe system may include more than two probe assemblies 100. For example,in some embodiments, three probe assemblies 106 may be used, and theprobe assemblies 106 may be operated in a triphasic mode, whereby thephase of the current being supplied differs for each probe assembly 106.In further embodiments, the system 100 may be configured to control oneor more of the flow of current between electrically conductivecomponents and the current density around a particular component. Insuch embodiments, the system 100 may be configured to alternate betweenmonopolar configurations, bipolar configurations, or quasi-bipolarconfigurations during a treatment procedure.

As a particular example, to treat tissue of a patient's body accordingto an exemplary embodiment of the present subject matter, the energydelivery device 192 of each of two probe assemblies 106 may be insertedinto the patient's body, e.g., using an introducer and stylet asdescribed herein. Once a power source, such as the generator 102, isconnected to the probe assemblies 106, a stimulating electrical signalmay be emitted from either of the electrodes 192 to a dispersiveelectrode or to the other electrode 192. This signal may be used tostimulate sensory nerves, where replication of symptomatic pain wouldverify that the tissue, such as an intervertebral disc, is pain-causing.Simultaneously, the cooling fluid may be circulated through the internallumens 136, 138 of the probe assemblies 106 via the pump assemblies 122and energy may be delivered from the RF generator 102 to the tissuethrough the energy delivery devices 192. In other words, radiofrequencyenergy is delivered to the electrodes 192 and the power is alteredaccording to the temperature measured by the temperature sensing elementin the tip of the electrodes 192 such that a desired temperature isreached between the distal tip regions 190 of the two probe assemblies106. During the procedure, a treatment protocol such as the coolingsupplied to the probe assemblies 106 and/or the power transmitted to theprobe assemblies 106 may be adjusted and/or controlled to maintain adesirable treatment area shape, size and uniformity. More specifically,actively controlling energy delivered to the tissue by controlling bothan amount of energy delivered through the energy delivery devices 192and individually controlling the flow rate of the pump assemblies 122.In further embodiments, the generator 102 may control the energydelivered to the tissue based on the temperature measured by thetemperature sensing element(s) in the distal tip region 190 of the probeassemblies 106 and/or based on impedance sensors.

Referring now to FIG. 4, a schematic diagram is provided of the pumpsystem 120, according to an exemplary embodiment of the present subjectmatter. As shown in FIG. 4, the pump system 120 includes four pumpassemblies 122. Each pump assembly 122 comprises a pump motor 150, apower supply cable 152 for supplying power to the pump motor 150, and apump head 154 driven by the motor 150. Thus, the pump system 120illustrated in FIG. 4 includes a first pump assembly 122 a having afirst motor 150 a, a first power supply cable 152 a, and a first pumphead 154 a; a second pump assembly 122 b having a second motor 150 b, asecond power supply cable 152 b, and a second pump head 154 b; a thirdpump assembly 122 c having a third motor 150 c, a third power supplycable 152 c, and a third pump head 154 c; and a fourth pump assembly 122d having a fourth motor 150 d, a fourth power supply cable 152 d, and afourth pump head 154 d.

In each pump assembly 122, the motor 150 is directly coupled to the pumphead 154 to drive the fluid pumping mechanism of the assembly 122, andthe pump head 154 has a rotor assembly that may rotate clockwise orcounterclockwise. A tubing 156 (FIG. 2) may be loaded into the pump head154, and the pump head rotor assembly acts on, e.g., compresses, thetubing 156 to pump fluid from a fluid reservoir 158 (FIG. 2) through thetubing 156 and the cooling circuit 140, e.g., to cool the distal end 194of the probe assembly 106. More particularly, in exemplary embodiments,the pump assemblies 122 are peristaltic pump assemblies. As such, foreach pump assembly 122, tubing 156 extends through the pump head 154,and the pump head 154, driven by the motor 150, compresses the tubing156 to draw a cooling fluid from the fluid reservoir 158 and pump thecooling fluid into the shaft supply tube or lumen 136 that delivers thecooling fluid to the distal end 194 of the energy delivery device 192 ofthe associated medical probe assembly 106, as previously described.

As described herein, the system 100 may comprise a plurality of probeassemblies 106 that each has a dedicated cooling circuit 140, where theflow of cooling fluid through the cooling circuit 140 is controlled by apump assembly 122. That is, the number of pump assemblies 122 may matchthe number of medical probe assemblies 106; for example, the system 100may include four probe assemblies 106 and four pump assemblies 122 asshown in FIGS. 2 and 4. However, not every probe assembly 106 of thesystem 100 may be operated during a procedure. For instance, a clinicianmay utilize only two probe assemblies 106 during a given procedure, suchthat only two probe assemblies 106 out of the four probe assemblies 106require cooling via their cooling circuits 140. Therefore, for the pumpassemblies 122 associated with probe assemblies 106 that are not in useduring the procedure, it would be desirable to not run the pump motor150 to drive the pump head 154, as no tubing 156 is loaded in the unusedpump head 154 because no cooling is needed for the associated probeassembly 106.

As illustrated in FIG. 4, a control unit 148, such as a controller,processor, or the like that may have a memory and be configured forexecuting programming instructions as described above, is provided thathelps determine whether tubing 156 is loaded into a pump head 154 and,if not, terminates power to the pump head 154. In some embodiments, thecontrol unit 148 may be onboard the generator 102, e.g., the controlunit 148 may be a control module of the controller 101. In otherembodiments, the control unit 148 may be a separate controller orprocessor onboard the pump system 120 or other suitable component of thesystem 100. Further, the control unit 148 may be configured forcontrolling whether power is supplied to the power supply cable 152 ofeach pump assembly 122, e.g., by controlling whether a switch in eachpower supply line is open or closed, as described herein.

Referring to FIGS. 4 and 5, a method for detecting tubing in a pumpassembly will be described, according to an exemplary embodiment of thepresent subject matter. FIG. 5 provides a flow diagram illustrating anexemplary method 500 for detecting tubing 156 in a pump assembly 122. Asshown at 502 in FIG. 5, the method 500 includes connecting a powersupply, such as power supply 126, to each of the plurality of pumpmotors 150 of the pump system 120. More specifically, the power supplycable 152 of each pump motor 150 is configured to connect to the powersupply 126, such that, as shown in the exemplary embodiment of FIG. 4,each power supply cable 152 a, 152 b, 152 c, 152 d is connected to thepower supply 126. At 502, the power supply cables 152 are placed inoperative connection with the power supply 126 such that electricalcurrent flows through each power supply cable 152. For instance, one ormore switches or the like may be disposed between each power supplycable 152 and the power supply 126 such that the power or current may beinterrupted to each power supply cable 152 individually. As an example,the power supply to the first power supply cable 152 a, which providespower to the first pump motor 150 a, may be interrupted or terminated,i.e., disconnected, thereby rendering the first pump motor 150 ainoperable, while the power supply to each of the remaining power supplycables 152 b, 152 c, 152 d is uninterrupted, i.e., the remaining powersupply cables 152 are connected to the power supply 126. In someembodiments, the pump motors 150 may begin to operate as soon as themotors 150 are connected to the power supply 126, but in otherembodiments, the method 500 also includes at 502 turning on the pumpmotors 150 when the motors 150 are connected to the power supply via thepower supply cables 152.

As illustrated at 504 in FIG. 5, the method 500 further includes sensinga motor current from each of the power supply cables 152. Referring toFIG. 4, a current sensor 182 is connected to, or in operativecommunication with, each of the power supply cables 152 such that thecurrent sensor 182 can measure the current draw by each pump motor 150.In some embodiments, the current sensor 182 simultaneously measures eachsupply current, but in other embodiments, the current sensor 182multiplexes between each power supply cable 152 to measure the currentand, thus, includes a multiplexer (or mux). In still other embodiments,the pump system 120 comprises a plurality of current sensors 182, andone current sensor 182 of the plurality of current sensors 182 ispositioned at each power supply cable 152 of the plurality of powersupply cables 152 to measure the current through the power supply cables152. That is, an individual current sensor 182 may be provided to senseor measure the current draw by one pump motor 150, and an individualcurrent sensor 182 is provided for each pump motor 150 of the pumpsystem 120. Although primarily described herein with respect to a singlecurrent sensor 182, the present subject matter may be adapted for aplurality of current sensors 182, as will be readily understood by onehaving ordinary skill in the art.

The current sensor 182 is connected to the control unit 148 tocommunicate a motor current or motor current signal from each powersupply cable 152 to the control unit 148. As depicted in FIG. 4, thecontrol unit 148 of the exemplary embodiment includes three modules,engines, or software subroutines for processing the motor currentsignals—a filter 174, a fast Fourier Transform (FFT) engine 176, and apost-processing engine 178. Referring to FIG. 5, the method 500 includesat 506 passing the motor current from each of the power supply cables152 through the filter 174 to produce a filtered current signal fromeach of the power supply cables 152. In various embodiments, the filter174 may be a low-pass filter or a Kalman filter. A suitable filter 174may be selected based on, e.g., a typical frequency of the motors 150,such that the filter 174 can filter out signal noise based on the motor150. For instance, the motors 150 may be stepper motors, which exhibit astepping frequency, and the cutoff frequency for the filter 174 may bebased on the motor operating speed and step size.

As shown at 508 in FIG. 5, the method 500 also includes passing thefiltered current signal from each of the power supply cables 152 throughthe FFT engine 176 to produce a transformed signal from each of thepower supply cables 152. More specifically, the FFT engine 176transforms the current measured from the power supply cables 152 in thetime domain to the frequency domain. Next, as shown at 510, the methodincludes determining whether a tubing 156 is loaded in each pump head154. In the depicted embodiment, the transformed signals pass from theFFT engine 176 to the post-processing engine 178, which determineswhether the transformed signal from each power supply cable 152 containsone or two fundamental frequencies. More particularly, as illustrated inFIG. 6, when no tubing 156 is loaded in a pump head 154, the transformedcurrent signal from the power supply cable 152 supplying the pump motor150 associated with that pump head 154 exhibits only one fundamentalfrequency, which represents the stepping frequency of the motor 150. Thewaveform shown in the oscilloscope photographs of FIG. 6 is largely AC(alternating current) at a single fundamental frequency that representsthe stepping frequency of the motor 150; the y-axis is the normalizedcurrent value and the x-axis is time. The upper and lower photographs inFIG. 6 are the same, but in the lower photograph, a dotted line has beenadded to more clearly delineate the waveform.

However, when tubing 156 is loaded in a pump head 154, the transformedcurrent signal from the power supply cable 152 supplying the pump motor150 associated with that pump head 154 exhibits two fundamentalfrequencies. The two fundamental frequencies represent the steppingfrequency of the motor 150 and the frequency with which the pump headrotor assembly moves over the tubing 156, which is a lower frequencythan the motor's stepping frequency. As shown in the oscilloscopephotographs of FIG. 7, the stepping frequency of FIG. 6 is still presentbut is overlaid on a lower frequency. The lower frequency, representingthe rotor assembly rollers moving over the tubing 156 as described, iscalled out by the dotted line in the lower photograph (which isotherwise identical to the upper photograph).

Thus, the post-processing engine 178 can use the presence of the lowerfrequency to determine that tubing is present in a pump head 154. Stateddifferently, if the post-processing engine 178 observes only onefundamental frequency in the transformed signal from a power supplycable 152 to a pump motor 150, then the post-processing engine 178determines the pump head 154 associated with that pump motor 150 doesnot have tubing 156 loaded in the pump head 154. Then, as shown at 512,the associated pump motor 150 is disconnected from the power supply 126.That is, each pump head 154 without tubing 156 loaded in the pump head154 does not need to be running and, therefore, the pump motor 150driving such empty pump heads 154 can be stopped, turned off, ordisconnected from the power supply 126. As previously discussed, thepower supply 126 may be interrupted or terminated to a given pump motor150 by, e.g., opening a switch in the power supply cable 152 supplyingpower to the motor 150.

Nonetheless, if the post-processing engine 178 observes two fundamentalfrequencies in the transformed signal from a power supply cable 152 to apump motor 150, e.g., a higher frequency consistent with a steppermotor's stepping frequency and a lower frequency consistent with a rotorassembly rolling over a tube, then the post-processing engine 178determines the pump head 154 associated with that pump motor 150 doeshave tubing 156 loaded in the pump head 154. Thus, the control unit 148determines such pump motors 150 should remain connected to the powersupply 126, and in some embodiments, the current sensor 182 may continueto sense the current through the connected power supply cables 152 andsend the current signal(s) to the control unit 148 for processing. Insome embodiments, as shown at 514, the lower frequency portion of thetransformed current signal from a power supply cable 152 of a pump motor150 driving a tubing-loaded pump head 154 also may be used to calculateor determine the speed, in revolutions per minute (RPM), of the pumpmotor 150. More specifically, the lower frequency, representing thefrequency with which a roller of the pump head rotor assembly passesover the tubing 156, is determined from the transformed current signaland may be denoted f_L. The speed of the associated pump motor 150 maybe calculated using the following equation:

${RPM} = {\left( \frac{f\_ L}{R} \right) \times 60}$

where R is the number of rollers on the pump head rotor assembly. Thus,the lower frequency f_L both denotes the presence of tubing 156 in theassociated pump head 154 and can be used to determine the operatingspeed (or RPM) of the associated pump motor 150.

It will be appreciated that the foregoing method may be applied to eachpump assembly 122 of the pump system 120 such that the pump motor(s) 150of only the pump assembly(ies) 122 in which tubing is loaded are runningduring a procedure. As an example, at the beginning of a procedureutilizing two cooled probe assemblies 106, all of the pump assemblies122 of the pump system 120 are connected to the power supply 126 suchthat all of the pump motors 150 begin to run or operate. Thus, in thedepicted exemplary embodiments, four pump motors 150 a, 150 b, 150 c,150 d are connected to the power supply 126 such that the motors 150begin to run and drive their associated pump head 154. The currentsensor 182 senses the current draw by each of the four pump motors,either simultaneously or by multiplexing as described herein, and sendthe current signal associated with each pump motor 150 to the controlunit 148. The modules or engines of the control unit 148 process thecurrent signals as described herein. Then, the control unit 148determines whether the first pump head 154 a is loaded with first tubing156 a, the second pump head 154 b is loaded with second tubing 156 b,the third pump head 154 c is loaded with third tubing 156 c, and thefourth pump head 154 d is loaded with fourth tubing 156 d. Because twocooled probe assemblies 106 are being used in the procedure as statedabove, only two of the pump heads 154 are loaded with tubing 156, so byanalyzing the current signals from all four pump motors 150, the controlunit 148 determines which two pump heads 154 are loaded and disconnectsthe pump motors 150 associated with the remaining two pump heads 154from the power source 126. For example, if the control unit 148determines the second and fourth pump heads 154 b, 154 d are loaded withtubing, the control unit 148 disconnects the first and third pump motors150 a, 150 c from the power supply 126, e.g., by opening a switch in thefirst and third power supply cables 152 a, 152 c. Further, as describedwith respect to method 500, the control unit 148 may determine theoperating speed of the second and fourth pump motors 150 b, 150 d usingthe lower fundamental frequency.

Detecting tubing using only pump motor supply current thresholds wouldbe challenging due to the minute difference in supply current thresholdsbetween a pump head 154 operating with tubing 156 and a pump head 154operating without tubing 156. For instance, for a pump head 154 rotatingat 140 RPM, a pump motor 150 may draw on average 300 mA (300 milliamps)without tubing 156 and approximately 310 mA (310 milliamps) with tubing156, within a noise floor of 10-20 mA (10-20 milliamps). Thus, it is notpossible to effectively and repeatedly distinguish between a loaded andunloaded pump head 154 using only the difference in pump motor supplycurrent.

Accordingly, the present subject matter provides a system and method fordetecting whether tubing is present in a pump head of a pump assembly,using an effective and repeatable approach. More particularly, thedifference in the pump motor supply current waveform between loaded andunloaded pump heads is used to detect the presence of tubing. Asdescribed herein, in exemplary embodiments, the method comprisesoperating (or turning on) all pump motors of the pump system andobserving the fundamental frequencies (or waveforms) detectable in thecurrent draw by each pump motor. If tubing is not detected in a pumphead, that pump motor is rendered inoperable (or turned off), e.g., bydisconnecting the pump motor from its power supply. If tubing isdetected in a pump head, the pump motor associated with that pump headremains operable (or turned on) such that cooling fluid may be pumpedthrough the tubing. Thus, only those pump motors of the pump assembliesactually in use during a procedure utilizing the cooling fluid areoperated or activated (or turned on) for the majority of the procedure.

Deactivating the pump motors of the unused pump assemblies reduces thepower or energy consumption of the system and reduces wear on the pumpassemblies by running the assemblies only when needed. Further, thesafety of the system may be enhanced by reducing the number of rotatingparts, e.g., it is far less likely that an object will get twisted ortangled up in a rotor or rotor assembly that is not rotating, and thepump motor rotor and pump head rotor assembly of deactivated pumpassemblies are not rotating. Moreover, because the method for detectingthe presence of tubing essentially comprises using the difference in thesupply current waveform between loaded and unloaded pump heads todetermine whether a given pump head is loaded or unloaded, the approachdescribed herein may be implemented in some systems without the additionof any hardware. That is, the method is implemented through software,and the system need only a current sensor (which may be a standardhardware component of the system) to provide the necessary inputs to thesoftware to implement the method. Thus, the method described herein maybe a relatively low cost approach to ensuring only the needed pumpassemblies are operated during a procedure. In addition, the method fordetecting tubing described herein also provides means for assessingduring operation the rotational speed of the pump motors or pump headsthat are loaded with tubing. Other benefits and advantages of thepresent subject matter also may be realized by those of ordinary skillin the art.

Moreover, a system of the present subject matter may be used in variousmedical procedures where usage of an energy delivery device may provebeneficial. Specifically, the system of the present subject matter isparticularly useful for procedures involving treatment of back pain,including but not limited to treatments of tumors, intervertebral discs,facet joint denervation, sacroiliac joint lesioning or intraosseous(within the bone) treatment procedures. Moreover, the system isparticularly useful to strengthen the annulus fibrosus, shrink annularfissures and impede them from progressing, cauterize granulation tissuein annular fissures, and denature pain-causing enzymes in nucleuspulposus tissue that has migrated to annular fissures. Additionally, thesystem may be operated to treat a herniated or internally disrupted discwith a minimally invasive technique that delivers sufficient energy tothe annulus fibrosus to breakdown or cause a change in function ofselective nerve structures in the intervertebral disc, modify collagenfibrils with predictable accuracy, treat endplates of a disc, andaccurately reduce the volume of intervertebral disc tissue. The systemis also useful to coagulate blood vessels and increase the production ofheat shock proteins.

Using liquid-cooled probe assemblies 106 with an appropriate feedbackcontrol system as described herein also contributes to the uniformity ofthe treatment. The cooling distal tip regions 190 of the probeassemblies 106 helps to prevent excessively high temperatures in theseregions which may lead to tissue adhering to the probe assemblies 106 aswell as an increase in the impedance of tissue surrounding the distaltip regions 190 of the probe assemblies 106. Thus, by cooling the distaltip regions 190 of the probe assemblies 106, higher power can bedelivered to tissue with a minimal risk of tissue charring at orimmediately surrounding the distal tip regions 190. Delivering higherpower to energy delivery devices 192 allows tissue further away from theenergy delivery devices 192 to reach a temperature high enough to createa lesion and thus the lesion will not be limited to a region of tissueimmediately surrounding the energy delivery devices 192 but will ratherextend preferentially from a distal tip region 190 of one probe assembly106 to the other.

As has been mentioned, a system of the present subject matter may beused to produce a relatively uniform lesion substantially between twoprobe assemblies 106 when operated in a bipolar mode. Oftentimes,uniform lesions may be contraindicated, such as in a case where a tissueto be treated is located closer to one energy delivery device 192 thanto the other. In cases where a uniform lesion may be undesirable, usingtwo or more cooled probe assemblies 106 in combination with a suitablefeedback and control system may allow for the creation of lesions ofvarying size and shape. For example, preset temperature and/or powerprofiles that the procedure should follow may be programmed into thegenerator 102 prior to commencement of a treatment procedure. Theseprofiles may define parameters (these parameters would depend on certaintissue parameters, such as heat capacity, etc.) that should be used tocreate a lesion of a specific size and shape. These parameters mayinclude, but are not limited to, maximum allowable temperature, ramprate (i.e. how quickly the temperature is raised) and the rate ofcooling flow, for each individual probe. Based on temperature orimpedance measurements performed during the procedure, variousparameters, such as power or cooling, may be modulated, to comply withthe preset profiles, resulting in a lesion with the desired dimensions.

Similarly, it is to be understood that a uniform lesion can be created,using a system of the present subject matter, using many differentpre-set temperature and/or power profiles which allow the thermal doseacross the tissue to be as uniform as possible, and that the presentsubject matter is not limited in this regard.

It should be noted that the term radiopaque marker as used hereindenotes any addition or reduction of material that increases or reducesthe radiopacity of the device. Further, the terms probe assembly,introducer, stylet etc. are not intended to be limiting and denote anymedical and surgical tools that can be used to perform similar functionsto those described. In addition, the subject matter is not limited to beused in the clinical applications disclosed herein, and other medicaland surgical procedures wherein a device of the present subject matterwould be useful are included within the scope of the present subjectmatter.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Although the present subject matter has been described in conjunctionwith specific embodiments thereof, it is evident that many alternatives,modifications and variations will be apparent to those skilled in theart. Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

What is claimed is:
 1. A method for detecting tubing in a pump assemblyof a pump system, the method comprising: connecting a power supply toeach of a plurality of pump motors of the pump system, each pump motorof the plurality of pump motors having a power supply cable configuredto connect to the power supply, each pump motor of the plurality of pumpmotors driving a pump head of a plurality of pump heads of the pumpsystem; sensing a motor current from each of the power supply cables;determining whether tubing is loaded in each pump head and, if tubing isnot loaded in a pump head, then disconnecting from the power supply thepower supply cable of the pump motor associated with the pump head inwhich tubing is not loaded.
 2. The method of claim 1, furthercomprising: passing the motor current from each of the power supplycables through a low-pass filter to produce a filtered current signalfrom each of the power supply cables, wherein the motor currents arepassed through the low-pass filter prior to determining whether tubingis loaded in each pump head.
 3. The method of claim 2, furthercomprising: passing the filtered current signal from each of the powersupply cables through a fast Fourier Transform engine to produce atransformed signal from each of the power supply cables, wherein thefiltered current signals are passed through the fast Fourier Transformengine prior to determining whether tubing is loaded in each pump head.4. The method of claim 3, further comprising: passing the transformedsignal from each of the power supply cables through a post-processingengine to determine whether tubing is loaded in each pump head.
 5. Themethod of claim 4, wherein determining whether tubing is loaded intoeach pump head comprises determining how many fundamental frequenciesare observed with respect to each transformed signal
 6. The method ofclaim 5, wherein tubing is loaded into a pump head of the plurality ofpump heads if two fundamental frequencies are observed.
 7. The method ofclaim 5, wherein tubing is not loaded into a pump head of the pluralityof pump heads if only one fundamental frequency is observed.
 8. Themethod of claim 1, further comprising: passing the motor current fromeach of the power supply cables through a Kalman filter to produce afiltered current signal from each of the power supply cables, whereinthe motor currents are passed through the Kalman filter prior todetermining whether tubing is loaded in each pump head.
 9. The method ofclaim 8, further comprising: passing the filtered current signal fromeach of the power supply cables through a fast Fourier Transform engineto produce a transformed signal from each of the power supply cables,wherein the filtered current signals are passed through the fast FourierTransform engine prior to determining whether tubing is loaded in eachpump head.
 10. The method of claim 9, further comprising: passing thetransformed signal from each of the power supply cables through apost-processing engine to determine whether tubing is loaded in eachpump head.
 11. The method of claim 10, wherein determining whethertubing is loaded into each pump head comprises determining how manyfundamental frequencies are observed with respect to each transformedsignal
 12. The method of claim 11, wherein tubing is loaded into a pumphead of the plurality of pump heads if two fundamental frequencies areobserved.
 13. The method of claim 11, wherein tubing is not loaded intoa pump head of the plurality of pump heads if only one fundamentalfrequency is observed.
 14. The method of claim 1, wherein the motorcurrent from each of the power supply cables is sensed by a currentsensor.
 15. The method of claim 1, wherein the pump system comprises aplurality of pump assemblies, each pump assembly configured to pump acooling fluid to a medical probe assembly of a plurality of medicalprobe assemblies, and wherein each medical probe assembly comprises aprobe having an energy delivery device for delivering energy to apatient's body, the cooling fluid pumped to a distal end of the energydelivery device.
 16. A system for detecting the presence of tubingwithin a pump head of a plurality of pump heads, the system comprising:a plurality of pump assemblies, each pump assembly comprising: a pumpmotor, a power supply cable for supplying power to the pump motor, andone pump head of the plurality of pump heads, wherein the pump motordrives the pump head; and a controller for controlling whether power issupplied to the power supply cable of each pump assembly, the controllerconfigured for connecting a power supply to each power supply cable,sensing a motor current from each of the power supply cables,determining whether tubing is loaded in each pump head and, if tubing isnot loaded in a pump head, then disconnecting from the power supply thepower supply cable of the pump motor associated with the pump head inwhich tubing is not loaded.
 17. The system of claim 16, wherein thecontroller is further configured for, prior to determining whethertubing is loaded in each pump head: passing the motor current from eachof the power supply cables through a low-pass filter to produce afiltered current signal from each of the power supply cables; passingthe filtered current signal from each of the power supply cables througha fast Fourier Transform engine to produce a transformed signal fromeach of the power supply cables; and passing the transformed signal fromeach of the power supply cables through a post-processing engine todetermine whether tubing is loaded into the respective pump head. 18.The system of claim 16, wherein the controller is further configuredfor, prior to determining whether tubing is loaded in each pump head:passing the motor current from each of the power supply cables through aKalman filter to produce a filtered current signal from each of thepower supply cables; passing the filtered current signal from each ofthe power supply cables through a fast Fourier Transform engine toproduce a transformed signal from each of the power supply cables; andpassing the transformed signal from each of the power supply cablesthrough a post-processing engine to determine whether tubing is loadedinto the respective pump head.
 19. The system of claim 16, furthercomprising: a plurality of current sensors, one current sensorpositioned at each power supply cable of the plurality of power supplycables to measure the current through the power supply cables.
 20. Amethod for detecting tubing in a pump assembly, the method comprising:connecting a power supply to a pump motor of the pump assembly, the pumpmotor having a power supply cable for connecting to the power supply,the pump motor driving a pump head of the pump assembly; sensing a motorcurrent from the power supply cable; transforming the motor current in atime domain to a frequency domain; determining whether tubing is loadedin the pump head and, if tubing is not loaded in the pump head, thendisconnecting the power supply cable from the power supply; andcalculating a speed of the pump motor if tubing is loaded in the pumphead, wherein determining whether tubing is loaded in the pump headcomprises determining how many fundamental frequencies are observable inthe transformed motor current.